teach instcombine to remove allocated buffers even if there are stores, memcpy/memmove/memset, and objectsize users.

This means we can do cheap DSE for heap memory.
Nothing is done if the pointer excapes or has a load.

The churn in the tests is mostly due to objectsize, since we want to make sure we
don't delete the malloc call before evaluating the objectsize (otherwise it becomes -1/0)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159876 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 49 insertions, 4 deletions

diff --git a/test/Transforms/InstCombine/malloc-free-delete.ll b/test/Transforms/InstCombine/malloc-free-delete.ll
index eae973df0a..4e3217dc2d 100644
--- a/test/Transforms/InstCombine/malloc-free-delete.ll
+++ b/test/Transforms/InstCombine/malloc-free-delete.ll
@@ -1,17 +1,17 @@
 ; RUN: opt < %s -instcombine -S | FileCheck %s
 ; PR1201
 define i32 @main(i32 %argc, i8** %argv) {
+; CHECK: @main
     %c_19 = alloca i8*
     %malloc_206 = tail call i8* @malloc(i32 mul (i32 ptrtoint (i8* getelementptr (i8* null, i32 1) to i32), i32 10))
     store i8* %malloc_206, i8** %c_19
     %tmp_207 = load i8** %c_19
     tail call void @free(i8* %tmp_207)
     ret i32 0
-; CHECK-NOT: malloc
-; CHECK-NOT: free
-; CHECK: ret i32 0
+; CHECK-NEXT: ret i32 0
 }
 
+declare noalias i8* @calloc(i32, i32) nounwind
 declare noalias i8* @malloc(i32)
 declare void @free(i8*)
 
@@ -26,13 +26,24 @@ define i1 @foo() {
 
 declare void @llvm.lifetime.start(i64, i8*)
 declare void @llvm.lifetime.end(i64, i8*)
+declare i64 @llvm.objectsize.i64(i8*, i1)
+declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+declare void @llvm.memmove.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
+declare void @llvm.memset.p0i8.i32(i8*, i8, i32, i32, i1) nounwind
 
-define void @test3() {
+define void @test3(i8* %src) {
 ; CHECK: @test3
 ; CHECK-NEXT: ret void
   %a = call noalias i8* @malloc(i32 10)
   call void @llvm.lifetime.start(i64 10, i8* %a)
   call void @llvm.lifetime.end(i64 10, i8* %a)
+  %size = call i64 @llvm.objectsize.i64(i8* %a, i1 true)
+  store i8 42, i8* %a
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %a, i8* %src, i32 32, i32 1, i1 false)
+  call void @llvm.memmove.p0i8.p0i8.i32(i8* %a, i8* %src, i32 32, i32 1, i1 false)
+  call void @llvm.memset.p0i8.i32(i8* %a, i8 5, i32 32, i32 1, i1 false)
+  %alloc2 = call noalias i8* @calloc(i32 5, i32 7) nounwind
+  %z = icmp ne i8* %alloc2, null
   ret void
 }
 
@@ -46,3 +57,37 @@ define void @test4() {
   call void @free(i8* %C)
   ret void
 }
+
+; CHECK: @test5
+define void @test5(i8* %ptr, i8** %esc) {
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call i8* @malloc
+; CHECK-NEXT: call void @llvm.memcpy
+; CHECK-NEXT: call void @llvm.memmove
+; CHECK-NEXT: store
+; CHECK-NEXT: call void @llvm.memcpy
+; CHECK-NEXT: call void @llvm.memmove
+; CHECK-NEXT: call void @llvm.memset
+; CHECK-NEXT: store volatile
+; CHECK-NEXT: ret
+  %a = call i8* @malloc(i32 700)
+  %b = call i8* @malloc(i32 700)
+  %c = call i8* @malloc(i32 700)
+  %d = call i8* @malloc(i32 700)
+  %e = call i8* @malloc(i32 700)
+  %f = call i8* @malloc(i32 700)
+  %g = call i8* @malloc(i32 700)
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %ptr, i8* %a, i32 32, i32 1, i1 false)
+  call void @llvm.memmove.p0i8.p0i8.i32(i8* %ptr, i8* %b, i32 32, i32 1, i1 false)
+  store i8* %c, i8** %esc
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %d, i8* %ptr, i32 32, i32 1, i1 true)
+  call void @llvm.memmove.p0i8.p0i8.i32(i8* %e, i8* %ptr, i32 32, i32 1, i1 true)
+  call void @llvm.memset.p0i8.i32(i8* %f, i8 5, i32 32, i32 1, i1 true)
+  store volatile i8 4, i8* %g
+  ret void
+}